Yes, that is precisely what I mean.
Can the TX2 4GB module auto boot on devkit?
No, neither card can auto boot from the devkit, as I have not taken the necessary steps to enable that on the devkit carrier board.
Have you check the TX2 series product design guide in DLC? Auto-power-on part is same to TX2 and TX2 4GB as below description.
Yes. The design of the board was outsourced to a company in a neighboring city that designs PCBs regularly, and it should follow the design guide.
4.8.1 Jetson TX2/TX2 4GB Auto-Power-On Details
For Jetson TX2/TX2 4GB, to enable this feature, the CHARGER_PRSNT# pin should be tied to GND. To power the system on without a power button, a specific sequence is required between the time the VDD_IN power is connected and the CHARGER_PRSNT# pin on the module is driven low. The CHARGER_PRSNT# pin connects to the module PMIC and requires a minimum delay of 300ms from the point VDD_IN reaches its minimum level (5.5V) before it can be driven low. Jetson TX2/TX2 4GB includes circuitry on the module to support Auto-Power-On.
Does this mean that the CHARGER_PRSNT# (PIN A49 in the Jetson TX2 datasheet) has to be connected to GND from the start, or that it must start HI, then driven LO at least 300ms after VDD_IN hits 5.5V?
The following two sentences seem contradictory to me:
For Jetson TX2/TX2 4GB, to enable this feature, the CHARGER_PRSNT# pin should be tied to GND.
The CHARGER_PRSNT# pin connects to the module PMIC and requires a minimum delay of 300ms from the point VDD_IN reaches its minimum level (5.5V) before it can be driven low.
I’m by no means an expert when it comes to designing PCBs, but I do have a decent general knowledge when it comes to electronics, and I’m still confused by the wording in chapter 4.8.1.
Could you please elaborate/explain the auto boot sequence a bit more clearly for me?
I can see from the schematics of the board that it is designed with PIN A49 connected straight to GND, and I have also measured with the continuity check on a multimeter to confirm this.
As an aside, I can say that the RFID reader powers up when the TX2 4GB is on the board. The power management circuit on the board waits for the CARRIER_PWR_ON signal before transforming 12V to 5V and 3V3 (at least as far as I can understand from the schematic), so it looks like the TX2 4GB sends out the CARRIER_PWR_ON signal.
Thank you for your help so far!